BOYLE’S LAW

OBJECTIVE:

To determine the relationship between

pressure and volume by performing Boyle’s

Law experiment.

THEORY:

BOYLE’S LAWIf pressure, volume or temperature remains constant, the other two cannot be varied independently of each other. At a constant temperature, Boyle Law states

P V = const.

Boyles law may be proved by a gas thermometer.

The gas thermometer has a hand pump to generate pressure at the open end of the tube.

P = h Hg * ρ Hg * g

h Hg = Height of mercury seal ρ Hg = Density of mercury = 13.6 g cm-3

g = 9.8 m/s2 = acceleration of free fallVolume of enclosed air in the column

V = ∏ * d2 * h 4 d = 2.7 mm = Inside diameter of the capillary

HOW TO CALCULATE THE PRESSURE

P Hg = h Hg * ρ Hg * g = 13.6 gcm-3* 9.8 m/s2 * 11mm = 15 Pa

The pressure P may now be calculated byP = P0 + P Hg + ∆P

Then, it may be represented as a function of V

Where,

V= ∏ * d2 * h 4

TOOLS:

Gas thermometer

Graphing paper

Pencil

Pen

Eraser

Calculator

Ruler

STEPS:

1. Read height h Hg from the scale of gas thermometer.

2. Generate pressure with hand pump, increasing it step by step.

3. Read height ‘h’ of the air column each time and record it.

DATA:

Outside pressure = P0 = 1011 hPa Height of mercury seal = h Hg = 11mm

TABLE 1Height of the enclosed quantity of air as a function of pressure.

∆P (hPa) h (cm) h (mm)

0

-10

-20

-30

-40

P = P0 + PHg +∆P

Where:P = PressureP0 = Atmospheric Pressure (1011 hPa)

PHg = Pressure of Mercury in a gas thermometer (15 hPa)

∆P = Change of pressure

V= π d2 × h 4Where:

V = Volumeπ = 3.14d = diameter (2.7 mm)h = height of Mercury column

V (mm 3 ) P (hPa)

TABLE 2 From Table 2 the chart may be

drawn.